Function disconnectedCallback

packages/reactive-element/src/reactive-element.ts:1159–1161

* Allows for `super.disconnectedCallback()` in extensions while * reserving the possibility of making non-breaking feature additions * when disconnecting at some point in the future. * @category lifecycle

()

   * @category lifecycle
   */
  disconnectedCallback() {
    this.__controllers?.forEach((c) => c.hostDisconnected?.());
  }

  /**
   * Synchronizes property values when attributes change.